I agree. I think Adstar's exclusionary approach is unfortunate and unnecessary. C20's sense of responsibility for his family is certainly not selfish. But there is definitely a fine line, one only God's guidance can allow one to walk with a pure conscience.
A real life example of why Adstar's point may be valid: A local farmer, conscious of a crime wave where farmers and their families are tortured, raped and killed to intimidate them from their land, hears a suspicious noise outside at the early hours of the morning. He decides to take action and fires a shot from his bedroom window. It turns out that he fatally wounded his only daughter, who was leaving early to surprise a friend on his birthday.
This is not self-defence as we mostly imagine it, but it falls under the same category. In similar cases, we usually read of the farmer trying to protect his daughter while his wife is being raped or while he is being beaten with a spade, or trying to stop someone's bleeding while others go to find help because the phone lines have been cut. In all circumstances, these people - mostly devout Christians - would rather have that the dogs or the fences prevented unlawful entrance, or that they were able to overpower the terrorists before any damage was done, but it should not be easy to say they should sit idly by while war is waged on them over a period of years. That is why governments, peace forces, courts of justice and laws are set up in the first place - these are legitimate forms of authority, granted by God.
That farmer is spending years in prison for manslaughter now, mourning his only daughter, and with his wife left in the care of family. Adstar's approach would have prevented that tragedy. But another farmer has managed to overpower three armed intruders with the help of a farmhand, successfully saving the life of his whole family.
Who are the victims, and who will God justify? Laws prevent people from taking vengeance and being a law unto themselves, but they don't regulate who slaps whom on which cheek. When we have a choice, and while we can deliberate and set down legal procedures, we know what to do. Our faith allows us to identify and bear inequity and persecution and injustice, even to the point of death. But it can also allow us to know when the time is right to protect ourselves: such times do come (Eccles. 3:1-8), but "woe to the one through whom it comes".